NORFOLK, Va. (AP/WAVY) - Federal officials say a virus is likely what's causing hundreds of dead bottlenose dolphins to wash ashore along the East Coast.
During a conference call Tuesday, Dr. Teri Rowles with the National Oceanic and Atmospheric Administration confirmed 333 dolphins have been stranded between New York and Virginia since July. That number is more than nine times the historical average for the region during July and August.
Earlier this month, NOAA declared an unusual mortality event to provide additional resources to study what's causing the deaths.
Rowles works with the NOAA Fisheries marine Mammal Health and Stranding Response Program, and Tuesday she said the tentative cause of the deaths is the cetacean morbillivirus. Dolphins with morbillivirus typically experience skin lesions, brain infections and pneumonia.
Morbillivirus is passed from dolphin to dolphin, but cannot be transmitted to humans.
Of the 33 dolphins tested during this outbreak, 32 tested positive for suspected or confirmed morbillivirus.
Lab workers test the dolphins for the virus in three different ways:
- Histopathology -- looking for diagnostic lesions in lymph nodes, brain and lungs
- Mollecular methods -- polymerase chain reaction, which detects the genes of the virus
- Immunocytic chemistry -- looking for antibodies in tissues
NOAA says many of the East Coast dolphins younger than 26-years-old have limited to no immunity to this virus. So, if they are introduced to it, they don’t have the antibodies to protect themselves from illness.
Biologists still do not know where the virus may have started or why it started, but Rowles said there are a few theories being tossed around. One is that some of the large off-shore dolphins are passing the virus on to coastal dolphins.
Rowles said biologists are trying to pinpoint the first cases in the coastal populations, which happened in February or March of this year, and identify any environmental drivers that may have caused them.
The same virus killed off more than 700 dolphins in the 1980s.
Rowles said the highest number of dolphin strandings now is occurring in Virginia, which also happened in the 1980s breakout. Since that breakout, there have been two others in the Gulf of Mexico, but not nearly at the same magnitude.
The 1980s die-off was a significant event for migratory bottlenose dolphins and was followed by a long recovery process. It lasted from June 1987 to May 1988, and while it is not certain when the strandings will stop, Rowles said one could project the deaths to increase and continue into the spring of 2013.
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A company has been hired to complete the repairs to the Herbert C. Bonner Bridge on the Outer Banks, but how long those repairs will take remains unknown.
Drivers traveling between Hatteras Island and the mainland were forced to use an emergency ferry Wednesday, following the sudden closure of the Bonner Bridge Tuesday.
State officials say construction on a new Bonner Bridge has been delayed for years because of a legal battle with an environmental group.